Here is one heavily worn 1975 Bell Super Magnum three-quarter helmet. From what I can tell the Super Magnum is just a later variant of Bell’s original three-quarter helmet the 500-TX. In comparing helmets it seems the Super Magnum has a bit deeper of a side cut for better peripheral and probably had some updated safety features in the construction. This helmet does not feature any of the Toptex markings found on older Bell-Toptex helmets of the 1960s.
The Super Magnum is DOT and SHCA approved. This particular helmet would not be approved for much of anything safety related, except maybe taking a beer bottle over the head around a campfire.
This helmet has had some aftermarket stickers added, possibly by someone who raced in it at some point. 68 on both sides, blue reflective strips near the jaw line, and a Honda of Boulder, Colorado sticker on the back along with the original Bell front sticker and Super Magnum back. You can probably see from the pictures (and please examine them closely) this things been kicked around, banged on stuff, possibly crashed. On the riders left hand side, near the 6 the 8 and trailing off to the back there’s a series of three small chips that make it down to the foam core. Most other chips are just through the paint. On the back to the right of the Bell sticker there’s a patch of wear that looks like it was caused by some serious friction, like that of a tire. Inside all the soft protective foam is missing. The chin straps still hold tight, but the vinyl covering them is cracked and ratty. Marking on the strap is 7-75.
Currently available on the BCV eBay Store